摘要 |
There is described a system of optical repeated transmission comprising a signal transmission path comprising optical fibres (2, 4, 6 and 8) for transmitting signal light, and an optical amplifier comprising repeaters (3, 5, 7) disposed in the signal transmission path, and directly amplifying the signal light. In the described system, the amplification factor of the optical amplifier is not dependent on the direction of polarisation of the signal light that is input to it. |